This article throw light upon the seven major diseases caused by brinjal. The diseases are: 1. Bacterial Wilt 2. Phomopsis Blight 3. Brinjal Little Leaf 4. Shoot and Fruit Borer 5. Jassid/Leaf Hopper 6. Thrips 7. White Flies.
Disease # 1. Bacterial Wilt:
Dingaras Multiple Purple, Sinampiro from Philippines, Pusa Purple Cluster Singnath, Bholanath of NEH region of India and local cultivars from Orissa like Green Star, Blue Star and BB series varieties from OUAT, Bhubaneswar, Kopek (Java) and wild species, viz. Solarium melongena var. insanum, S. xanthocarpum, S. toxicarium, S. nigrum and S. sisymbriifolium.
Bacterial wilt of eggplant is a major disease causing heavy losses in eggplant production in the tropical, sub-tropical and temperate regions. In India, the coastal belts of Kerala, Tamil Nadu, Andhra, Pradesh and Orissa show greater manifestation of disease severity. Wilt is caused by Ralstonia Solanacearum, a soil borne bacteria which invades the host through wounds in roots or underground parts of the plant.
The characteristic symptoms include wilting of the foliage followed by collapse of the entire plants. The wilting is characterised by dropping and slightly yellowing of leaves and discolouration of vascular region. Drying of plants at flowering and fruiting is also common. The infected cut stem pieces when dipped in water, show of white milky stream of bacterial ooze coming out which is diagnostic symptom of bacterial wilt.
The disease rating scale is as follows:
0, Highly resistant: No wilting of plants
1, Resistant: 1-20% plants wilted
2, Moderately resistant: 21-40% plants wilted
3, Moderately susceptible: 41-60% plants wilted
4, Susceptible: 61-80% plants wilted
5, Highly susceptible: 7-80% plants wilted
Disease # 2. Phomopsis Blight:
Florida Market, Florida Beauty, Pusa Bhairav and wild species like S. xanthocarpum, S. indicum, S. gilo, S. khsianum, S. torum, S. sisymbriifolium and S. testiculatum
Disease # 3. Brinjal Little Leaf:
Singh (2004) has given detailed account of this disease which is caused by phytoplasma. If was first reported by K.M. Thomas and C.S. Krishna swami in 1939 in India. Early symptoms are light yellow colour of leaves. Infected leaves are thinner. Flower buds take an upright position instead of being pendulous. The flowers become phylloid, leaves become progressively smaller.
Stimulated axillary buds grow out into axillary shoots which in turn produce secondary and tertiary branches. The diseased plants have crowding of short branches and proliferation of smaller leaves giving a rosette appearance to the plant. Diseased plants exhibit phyllody. Infected plants normally do not bear fruits.
However, if any fruit is formed, it becomes hard and tough and fails to mature. It is transmitted by leaf hopper and also transmitted artificially by grafting. The disease has been seen to occur in eggplant fields in Kharif season in great severity in Pune. No resistant source is available.
Disease # 4. Shoot and Fruit Borer (Leucinodes Orbonalis):
Annamalai, Pant Samrat, Bhagyamati, Aushay, Pusa Purple Cluster, AM 62, S. gilo, S. anomalum (tolerant), S. indicum, S. incanum (resistant). This insect is a major pest in India and other Asian countries. Caterpillars make tunnel through shoot and fruit and a large portion of harvested fruits becomes non-marketable. The wilted shoots are easily visible. There may be small darkened holes surrounded with brownish area on fruit surface and/or fruit stalk.
The inside of the fruit is hollow and filled with frass. The larvae can be located in the wilted shoots. Larva can be found feeding inside. Fruit damage will not be obvious at this stage. The first indication is a small hole in the fruit stalk or in the fruit itself. This is where the insect has entered. Cutting fruit near this entry hole will lead to areas where the larvae has tunneled. The tunnels contain frass and insect remains.
The genotypes with high phenol content, high phenol oxidase activity, high glycoalkaloid content, low total soluble sugars and reducing sugars and low anthocyanin content (white fruit colour) are needed to breed resistant cultivars.
Disease # 5. Jassid/Leaf Hopper (Amrasca Biguttula Bigutulla):
Manjari Gota is reported to be tolerant. Infested leaves curl upwards along the margins. Outer leaf areas appear yellowish or burned. Leaves are extremely small and show a mosaic pattern of yellowing. Fruit set may be very low. These pests infest the lower surface of leaves. Commonly, if disturbed, they move very rapidly sideways and often hop. They are usually less than 13 mm long, with slender, tapered bodies of various colours and legs with rows of sharp spines.
Adults and immature are readily found on the undersides of leaves. Their nervous behaviour makes them difficult to catch. In warm climate multiple generations occur. Heavy infestation can cause yield reductions and total loss of crops. Some species transmit little leaf disease and mosaic virus.
Disease # 6. Thrips (Thrips Palmi):
Damage is obviously, on the underside of the lower leaves where areas appear brownish and dried up. In severe cases the entire leaf dries up. Similar damage is seen along the mid-vein on upper leaf surface. High level of resistance has been reported in wild Solanum species.
Disease # 7. White Flies (Bemisia Tabaci):
Varietal differences have been reported for antixenosis (attractivity) as well as for antibiosis against white fly. Morphological, biochemical or genetic basis of reported resistance is not understood.